A man believed to be the driver of the vehicle has been detained, Berlin police said.
At least one person has died and around 30 others injured after a car drove into a crowd in western Berlin before smashing through a shop window, emergency services say.
A man believed to be the driver of the vehicle has been detained, police said.
It is unclear whether the incident was an accident or the driver had intentionally driven into the crowd, Berlin police spokesman Martin Dams said.
The man had been driving a small Renault car, Germany’s Bild newspaper reported.
According to witnesses, he initially ran away and was stopped and handed over to police, it added.
Footage of the scene showed the silver car had crashed into the window display of a department store.
The fire service said around 30 people were injured in the incident – five with life-threatening injures.
Blankets covered what appeared to be a body in a cordoned-off area guarded by police.
Sky’s Europe correspondent Siobhan Robbins said the car went down the street and then hit a group of people, went back on to the road, mounted the kerb again before crashing into a shop.
It took place on Rankestrasse, near the main shopping district’s Breitscheidplatz, the scene of the 2016 Christmas market attack in which 11 people were killed.
Actor John Barrowman, who was at the scene with his husband Scott Gill, told Sky News he saw “a dead person in the middle of the road, covered up”.
“The person came on the pavement by the Levi store and the bank, then drove onto the street, hit the person and killed them in the street, then came back onto the kerb, went down the kerb, through the cafe area and then into the storefront,” he said.
“How horrible that this morning these people got up to just go through a regular day, they were going through their daily business. I mean we were shopping, but if you think if we’d have come out of that store one minute earlier…”
He said: “We are no experts but this looks intentional – by the way the car went on the pavement.”
“There were chairs and tables smashed on the pavement – just a trail of destruction,” said Mr Gill, a British architect.
“You could see the car had zig-zagged on and off the pavement on the way down.”
“For the first 10-20 minutes it was just sheer chaos,” he added. “We walked right through it without really realising what was happening.”
“We are quite shocked,” added Barrowman, fighting back tears. “To see people hurt, people who were just innocent and the senseless destruction by whoever has caused this.
“Whoever has done this is a horrible, horrible person… it is just a vicious thing to do.”
“We think we have witnessed a terrorist attack here in Berlin,” he tweeted earlier from the German capital.
“We’ve seen a car that came down the road and ended up in a storefront covering three city blocks. It’s pretty horrific.”
“There are police behind us, there are other police cars coming. There’s helicopters coming in. This is bad. This is serious,” he continued in video messages posted on social media.
“There are hundreds of emergency services that are in the area, blocking city block after city block, off. The cordon keeps expanding.”